Fisher 800c power supply issue

Discussion in 'Fisher' started by The Fuxtor, Jun 4, 2018.

  1. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    Hiya guys , been busy trying to restore a nice condition 800c but ran into an issue.... After installing new cans from Hayseed Hamfest, I plugged into a dbt with a 150watt incandescent light and hit the power. Bright ! Ok, thought I would try it on a variac at low power and see how the voltages looked. At 40 acv I noticed that C91 was getting very hot? I am 99% sure it has been installed in the same orientation as the original? Any advice on how to check where the issue would be?? I can only assume that that can is shot now too??
    I've attached a few pics, maybe something is obvious to the experienced eye with this unit....
    Charles
     

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  2. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    I think I may have found my problem? In pic 3233 I believe I may have installed the diodes wrong?? The diode on the left side, the cathode should be tied to the red wire side ???? Can anyone confirm?? Of course this pic is missing from the before shots.....:eek:
     
  3. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    The RED Wire from the Transformer gets connected BETWEEN CR6 and CR7, not at the Anode of CR6 like you have it. Also the .01uf cap at the anode of CR6 gets moved to the Cathode of CR6. Right now you got a DEAD SHORT from the TRANSFORMER! Move the Red wire and the lead of the cap to the cathode of CR6. And make damned sure that the terminal that the Cathode of CR6/Anode of CR7 is NOT grounded to the chassis.

    Larry
     
  4. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    ok, so that cap will be in the right spot after i put those diodes in the right orientation? Also what are the chances the can cap survived??
     
  5. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Look at the terminal strip. If the ground point (rivet) is on the lower Terminal, move the red lead and the end of the .01 cap to the upper terminal. DO NOT CHANGE ORIENTATION OF DIODES. (See pic. Yellow arrow points to where red wire and cap attach in this scenario.)

    If the Ground point is on the UPPER Terminal, then 1.) Reverse the vertical diode, 2.) leave the .01uf cap alone as is, 3.) move the Anode end of the Horizontal DIODE to the lower terminal so it, the cathode of the Vertical diode and the .01uf cap are all on the same terminal.

    The RED wire goes to the same place in both scenarios. At the junction of the diodes with the cap attached.

    800c PS.jpg
     
  6. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    I gotcha Larry, thanks..
     

     

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  7. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    Never ceases to amaze me , how well you know these old Fishers!! Thanks again!
     
  8. rufleruf

    rufleruf AK Subscriber Subscriber

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    I got a can cap from HH for the power supply in an X202B (2x 1000uf 50V) that was built with polarity backwards. Not sure it would register as a short, but when I powered it up it didn't take long to pop and let the smoke out.
     
  9. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    Did they replace that one?
     
  10. ncwalz

    ncwalz AK Subscriber Subscriber

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    Hi Fuxtor! Nice to see you back in Fisher forum! Didn’t think you’d be back after you sold that 400.
     
  11. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    Thanks! I stumbled upon an 800c, so I mean....what was I supposed to do??
    :banana:
    I got myself a pair of Heresey II to buddy up to it too!!
    Anything new in your collection?
     

     

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  12. rufleruf

    rufleruf AK Subscriber Subscriber

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    HH replaced the can. I actually got two with that problem. They replaced both. I wasted probably two hours dealing with it though
     
  13. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    You probably got my 400's bias caps. LOL!
     
  14. The Fuxtor

    The Fuxtor AK Subscriber Subscriber

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    Well got those diodes situated properly now and all seems good. I let the heated can revolt slowly with the variac for a few hours, so hopefully it will hang in there till I can replace it. Got the bias supply sitting at -17v and the old quad of RCA's are only reading 28ma but fairly consistent thru all 4 which is nice.
    Next on to the ibam!
     
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  15. ncwalz

    ncwalz AK Subscriber Subscriber

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    Got a Marantz 2270 and a 2275 which I have nicknamed “Dusty” and “Rusty”.
     
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